Bears general manager Phil Emery said he and Trestman hoped to fill out the rest of the coaching staff by the middle of next week. The Bears already have added two new assistants in Aaron Kromer (offensive coordinator and offensive line coach) and Joe DeCamillis (assistant coach and special-teams coordinator).

The biggest departure is that of Marinelli, who spent the past four seasons with the Bears and the past three seasons as defensive coordinator. Marinelli worked closely with Lovie Smith as the Bears led the NFL with 44 takeaways this season.

Trestman was asked whether he was open to converting to a 3-4 defensive scheme.

“I’m open to whatever it takes to stop football teams,” Trestman said. “But I also know what this football team has done over a number of years. They have excellent football players and they’ve been well coached.

“I don’t know the personnel on our football team right now, so to answer the question is premature. If you ask me three to four months from now, I’ll be in a much better position to answer that question.”

To be determined: Trestman offered high praise for Bears linebacker Brian Urlacher without committing to his future with the team.

Urlacher, 34, will become an unrestricted free agent when the new league year begins in March. He has said he wants to continue playing, but it’s uncertain whether the Bears will re-sign the veteran or replace him with a younger player.

“No. 1, I’ve watched the man play for a lot of years,” Trestman said. “He exemplifies what being a Chicago Bear is all about, and we all know that. When I step out of this room, we’ll begin to study and I’ll talk to Phil about where personnel fits on this football team and how it works. …

“I have a feeling that this guy has been a great player for this team. I recognize certainly what he’s meant to this locker room and to the fan base of the Chicago Bears. When we get done here, we’ll begin to try to answer some of those questions, and Phil will educate me to that.”

Come on down: As Trestman continues to assemble his coaching staff, look for several of his colleagues from the Canadian Football League to join the Bears.

Although some differences existed between the CFL and the NFL, Trestman said, teaching proper fundamentals remained the same.

“Yes, there will be some guys coming down,” Trestman said. “I’ve talked to them about it. But we haven’t locked it up because they may have other opportunities or decide to move in a different direction. But I would expect we’d have a few guys from the staff come south.”

Read option: Not only is Trestman a football coach, but he also is a published author.

In 2010, he wrote a book titled “Perseverance: Life Lessons on Leadership and Teamwork.” The book is available on his website – coachmarctrestman.com – and Trestman is able to track its sales.

“I’m going to let [Roberto] Garza know that he bought one book at 2 o’clock in the morning on the day that I was hired,” Trestman said with a grin as he named the Bears’ starting center. “I’ve got ‘Big Brother’ out there on the books.”